Original Research ARTICLE
Insight into the molecular mechanism of the transcriptional regulation of amtB operon in Streptomyces coelicolor
- 1Shanghai Institutes for Biological Sciences (CAS), China
In Streptomyces coelicolor, amtB transcription is promptly regulated by the global nitrogen regulator GlnR. Although the GlnR binding cis-element has been characterized in amtB promoter, consisting of three GlnR boxes of a3-b3, a1-b1 and a2-b2, its role in GlnR-mediated transcriptional regulation remains unclear. Here, we showed that GlnR had different binding affinity against each pair of GlnR binding sites in amtB promoter (i.e., a3-b3, a1-b1 and a2-b2 sites), and GlnR was able to bind a3-b3 and a1-b1, respectively, but not a2-b2 alone. Consistently, a2 was not a typical GlnR binding site and further experiments showed that a2 was non-essential for GlnR-mediated binding in vitro and transcriptional regulation in vivo. To uncover the physiological role of the three GlnR boxes, we then mutated the wild-type amtB promoter to a typical GlnR-binding motif containing two GlnR boxes (a3-b3-a2-b2), and found although the transcription of the mutated promoter could still be activated by GlnR, its increasing rate was less than that of the wild type. Based on these findings, one could conclude that the three GlnR boxes assisted GlnR in more promptly activating amtB transcription in response to nitrogen limitation, facilitating bacterial growth under nitrogen stresses.
Keywords: Streptomyces coelicolor, GlnR Box, AmtB, Transcriptional regulation, nitrogen metabolism, GlnR
Received: 30 Nov 2017;
Accepted: 02 Feb 2018.
Edited by:Marie-Joelle VIROLLE, Centre national de la recherche scientifique (CNRS), France
Reviewed by:Agnieszka Bera, Universität Tübingen, Germany
Juan F Martin, Universidad de León, Spain
Copyright: © 2018 Li, Liu, Wang, Wang, Zheng, Lu, Zhao and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Jin Wang, Shanghai Institutes for Biological Sciences (CAS), Shanghai, China, firstname.lastname@example.org